Twist-off preventer



J. A. ZUBLIN TWIST-OFF' PREVENTER May 20, 1930.

Filed June '11, 1928 Jl. I -1; i- @wu n M .M M H n fa .M 9 .a w. a .d f/ 12..... .t l f/ ff n u Il v M w HTTOENEY enemies may as, reso armes JOHN A. ZUBLIN, F LOS ANGELES, CALIFORNIA TWIST-OFF PREVENTER Application led June 11,

It is well known to those familiar with oil well drilling operations, that one of the most common sources of delay and consequent added expense in drilling due to iishing El jobs, results from the drill string breaking within the well. The drill string is ordinarily broken as a result of the bit having become fast or hung up in the bore hole, forcing the drill string to receive all of the torque l0 from the turn table. The application of this accumulating torsional strain to the drill string results in its being twisted throughout its length from the turn table to the bit, hence the common term twist 0H which is ordinarily ap lied to a break of this nature.

It has been my observation through both experimental and practical experience with the drill bits disclosed in my patent applications, Serial Numbers 54,875, 54,874; and

96,158 led on September 8, 1925, and March 20, 1926, respectively, that the powe'r applied to the drill string through, the' turn table, is not the only governing factor resulting in twist-offs. It has been observed in cases where the lower end of the drill string is held fast, as in the use of a bit similar to that disclosed in the above identified patent, that thedrill string will twist or wind up until the engine is stopped, showing that the power as ordinarily applied is insufficient to rupture the drill string. The above mentioned bit is provided with a plurality of projections which engage the bottom and sides of the bore hole, and prevent the bit from slipping by a projection with which it may be engaged, to receive a partial rotation from the accumulated torsional strain in the drill string.

If however the bit is of the class commonly known as the fish tail type in which it engages the bore hole on the bottom edge and the two vertical edges of the bit, it will be apparent that if such a bit, which has become fast in a bore hole through engagement with a projection therein, slips by the projection, the bit will travel at least one half a revolution at a tremendous velocity striking the proj ection with a force far greater than the force ordinaril applied to the turn table. The force with which the bit strikes the projection 50 in this case is the accumulated torsional 1928. Serial N0. 284,507.

energy in the wound up string of drill pipe, and may be easily demonstrated to be far in eXcess of the maximum capacity of an ordinary oil well power plant.

Let it be assumed that the drilling engine applies 100 horse power in a steady torque upon the drill string. If the bit is held fast for two seconds, the amount of energy stored in the drill string would amount to 200 horse power seconds. If, due to the increased torque, the bit should release, and make half a revolution in 1/50 of a second before engaging the obstacle again, the energy released would be 200 horse power seconds divided by 1/50 of a second or 10,000 horse power seconds. It is obvious that released energy of such magnitude applied as torque to the drill string when the bit strikes the projection, would subject the pipe to a strain far in eX- cess of its strength, resulting in its immediate rupture.

lt will be apparent from the foregoing reasoning, that if the accumulated torsional energy in the drill string resulting from its continued rotation after the bit has become fast, could be automatically released at some predetermined point, that the rupture of the drill string due to the sudden rotationand abrupt stop applied to the bit from such an accumulation of energy, could be prevented. v

It is therefore an object of this invention to develop a device which may be interposed in a drill string, and which will automatically permit the drill string to unwind when the torsional strain therein exceeds a predetermined limit.

It is a further object of this invention to develop a device which may be adjusted and which embodies a minimum of parts that may be easily and economically manufactured and assembled, providing a construction, the operation of which is efficient and dependable.

Other objects and advantages of this in-l vention will be better understood fromjthe following description of the accompanying drawings which are chosen for illustrative purposes only and in. which j Fig. 1 is a sectionall elevation of a bore hole showing a drill string, a drill bit and a twistoff preventer as being suspended therein.

Fig. 2 is an enlarged sectional elevation showing details in the construction of the twist-off preventer in Fig. 1.

Fig. 3 is an elevational view similar to Fig. 2 but showing the clutch members of a twistofil preventer in a position of disengagement.

Fig. 4 is a plan section taken in a plane represented by the line 4-4 of Fig. 2.

More particularly describing the invention as herein illustrated, it will be understood that the general construction of this device embodies two corresponding clutch members which are interposed in any suitable manner between the drill bit and the drill string and are held in yieldable engagement with one and another in such a manner as to permit the release or a partial reverse twisting movement of the drill string in the event the bit has become fast, thus permitting it to unwind at predetermined points preventing the accumulation of an undue internal torsional strain.

In the illustrated embodimentof this invention shown in the drawings, reference numeral 11 indicates a drill string having a twist-0H preventing device 12 interposed therein and a drill bit 13 suspended from the lower end thereof.

It will be understood that the twist-0H preventing device 12 may be positioned at any point within the drill string, but it is obvious that for the most eflicient operation, it should be placed at a position near the drill bit.

The details in the construction of this twist-off preventing device, will perhaps be best understood from a description of Figs. 2 to 4 inclusive, which show the construction as embodying what may be termed a clutch supporting member 14, the upper end 15 of which is provided with a collar adapted to receive the lower end of the drill string and the intermediate portion of which is provided with an outwardly extending flange 16, downwardly forming a shoulder 17, below which a mandrel or thrust bearing projection 18 extends, the thrust bearing projection 18 receives what may be termed a sliding clutch sleeve 19, this sleeve being slidable upon the mandrel 18 and held against rotation thereon by means such as a key 20, which is cooperatively mounted between the mandrel 18 and the clutch sleeve 19 as shown in Fig. 4.

The slidable clutch sleeve 19 is downwardly provided with a serieslof cam clutch faces 21, which engage cooperatively formed faces 21 upon the upper end of a lower rotatableclutch sleeve 22 which is suspended from the lower end of the mandrel or thrust bearing projection 18 and retained substantially against longitudinal movement thereon by means of any suitable locking device, a preferred form of which is illustrated as being comprised of oppositely disposed annular bearing races 23 and 23 formed in the inner surface of the clutch sleeve 22 and the outer surface of the mandrel respectively.

These races are adapted to receive a plurality of ball bearings 24 which are placed therein through apertures 25 in the rotatable clutch sleeve and are retained within the races by means such as the threaded plugs 26, placed in the apertures 25.4

The lower end 27 of the rotatable sleeve 22 is adapted to receive a drill bit 13 or a section 13 of the drill string which supports the drill bit and rotation is impart-ed to the drill bit 13 through the twist-off preventing device 12 from the main section of the drill string 11 by means ofthe cooperating clutch faces 21 and v21 which are held in yieldable engagement by means of a compression spring 30 interposed between an upper face 31 on the slidable clutch sleeve 19 and the lower shoulder 17 upon the iange 16.

It will be understood that the spring 30 may be adjusted to permit a disengagement of the clutch faces 21 and 21 by any predetermined relative torque between the clutch sleeves 19 and 22, adjustment being made by means of a plurality of spacing rings 32 which are positioned at one end of the spring 30.

For the purpose of delivering a circulating fluid from the drill string to the bit, 'thc twist-oft1 preventer 12 is provided with a circulating passage 34 cooperatively formed in the clutch supporting member 14 and th lower rotatable clutch sleeve 22. y

In the operation of this construction under normal circumstances, the bit will receive rotation from the drill string as was mentioned above, through th'e engaging clutch faces 21 and 21 but in the event the bit 13 becomes fast in the bottom of the bore hole as through engagement with a projection in the form of a rock or other solid member in the formation, the drill string will continue to receive rotation from the-rotary table and will tend to wind up as was mentioned above.

lVhen a predetermined torsional strain has been accumulated in the drill string such as may result from its winding up for say, 1/10 of a second, the spring 30 will yield to the cam action between the clutch faces permitting the clutch faces to ride over one another as is indicated in the position of the sleeves 19 and-22, shown in Fig. 3. This disengagement ofthe clutch members will cease as soon as the excess torsional strains have been eliminated. Under the action of the expand-v ing spring the clutch members will engage again as prior to the disengagement. The driller will raise the bit from the bottom of the hole for the purpose of drilling over again the spot where the bit has been fast or hun up.

It will be apparent therefore that with a construction of the type herein described,

that the accumulation of excessive torsional strain in`the drill string will be impossible and that the twist-oifs resulting therefrom 'as described above, will be eliminated, and it will be understood that while I have herein described one complete embodiment of my invention, that it is not limited to the precise construction set forth, but includes within its scope whatever changes fairly come within the-spirit of the appended claims.

I claim as my invention:

1. F or use in combination with a drill stringanda drill bit, a device adapted to be positioned in said drill string above said drill bit for releasing a torsional strain in said drill string, embodying: a clutch supporting member having a longitudinal passage therethrough and having a shoulder formed thereon; a slidable clutch sleeve ixed against rotation on said supporting member;` a cooperating rotatable clutch sleeve substantiallyiixed against longitudinal movement on v said supporting member and having a longitudinal passage adapted to register with said mentioned passage; and a compression spring interposed between said slidable clutch sleeve and the shoulder formed on said supporting member for holding said slidable clutch sleeve and said rotatable clutch sleeveiin yieldable engagement.

2. For use in `combination with a drill jection, in cooperative engagement with said slidable clutch sleeve, and having a bearing recess adapted to receive pressure engagement from said thrust bearing projection; and means for supporting said rotatable clutch sleeve in a substantially iixed longitudinal relation upon said projection.

In testimony whereof, lhave hereunto set my hand at Los Angeles, California, this 4th day of June, 1928.

` i JOHN A. ZUBLIN.

string and a drill bit, a device adapted to be positioned in said' 'drill string above said drill bit for releasing a torsional strain in said drill string, embodying aclutch supportin member havin a longitudinal passage t erethrough an ,having a shoulder formed thereon; a slidable clutch sleeve fixed against rotation on said supporting member; a cooperative rotatable clutch sleeve substantially fixed against longitudinal movementon said supporting member and having a longitudinal passage adapted to register with said mentioned passagea compression spring inl 'terposed between said slidable clutch sleeve 45 and the shoulder formed on said supporting member for holding said slidable clutch sleeve and said rotatable clutch sleeve in yieldable engagement and means for imparting pressure adjustment to `said compression sprini.

, 3. device for releasing torsional strain between two sections of a longitudinal rotat; ing member, embodying: a clutch supporting member having a longitudinal passage therethrough and having a shoulder and a thrust bearingl projection formed thereon; a compression spring surroundingsaid projection Y in engagement with said shoulder; a slidable clutch sleeve mounted on said projection in engagement with said 'spring opposite said shoulder; means preventing rotation bf said slidable clutch sleeve relative to said projection; a rotatable clutch sleeve having a`- l longitudinal passage adapted to register with i said mentioned passage mounted on said pro- 

